54

If your engine even has a problem carboning up, you don't clear it at cold start. Nor do you clear it by spinning the engine to redline. "Revving" isn't meaningful to diesel engine performance the way it is to sport gas engines and it doesn't help remove carbon. It's just a rationalization. To remove carbon, you want the engine working hard for 10-20 ...


47

Yes, this may be bad. The oil is not yet at the operating temperature, and the same is true for engine parts as well. I wouldn't redline a cold engine with cold oil. Your intention to clear carbon deposits is justified. But why don't you do this during a drive? That way, the engine and oil have had a chance to heat up to operating temperature. By the way, ...


27

As others have noted, the O/D button is used to disable and enable the overdrive gear. What hasn't been discussed is why you might want to use this button, and in what circumstances. The vehicle you have shown is a 9th generation Toyota Corolla. From the user's manual (which should always be your first source of information for your vehicle, specifically) ...


24

The "OD" means over drive. It's the last gear in your transmission. When the indicator shows as "off", it means the transmission won't go into that gear. Overdrive provides a mechanical advantage for the engine to run at a slower speed when traveling at highway speeds. This allows for better fuel economy. As I stated, it is the last gear in the transmission ...


14

I'm not entirely sure a rev limiter will help protect you if you downshift at a speed higher than the gear you've selected is intended for. If you manage to lift the clutch, even without any fuel, throttle or spark, you could do some fairly significant damage. To answer the question regarding the rev limiter. If a carburetor or mechanical fuel injection ...


13

Traditional rev limiters work by controlling the ignition and/or fuel. Ignition Control Retarding the spark (smoother) Completely cutting the spark (more aggressive) Fuel Control - Amount of fuel thrown in is controlled. This is used very carefully as effects of running lean at such high RPM can be detrimental to the engine health. In fact, lot ...


12

The RPMs would certainly increase but the mechanical components would be prevented from exceeding maximum RPMs by a rev-limiter. Rev-limiters are built into the ECU (computer) of the car. When an engine is spinning at its maximum RPM set by the manufacturer, the ECU will not send a spark to particular cylinders to prevent the engine from spinning faster ...


10

While most new electronically controlled vehicles probably do have a rev-limiter built in, this doesn't mean you cannot go past the red-line of the engine. The red-line is the theoretical maximum you ever want your engine to run at and is the limit at which your engine is designed to work. Beyond this point one of the first bad things which occur is called ...


6

Not intended to be a great answer but just so you know the information is there... From the description of the rev-limiter tag: Device used in the ignition system to limit the rotations per minute (RPM) or engine speed. In newer electronically controlled powertrains, this can be done through programming of the powertrain control unit/module (PCU/PCM). ...


4

I'm betting your Jag is Drive-By-Wire (DBW), meaning, there isn't a direct connection between you and the throttle. If so, the gas pedal rheostat is probably telling the computer you are pressing it, causing the throttle to go up. You could possibly test the gas pedal by unplugging it and checking for even/smooth operation by putting an ohmmeter on the leads....


4

As @Paulster2 explains it is overdrive. The reason you have a button to disable it is that there are situations where you need more torque, like pulling a trailer or carrying a heavy load. Overdrive reduces your torque, giving your engine less mechanical advantage.


3

Given you say "I'm pretty sure that it went past the redline before" I am going to assume that you aren't sure it ever did it. Cars are not only not designed from the factory to exceed the redline, they are designed with safeguards to prevent the ability to do so. This could be done several ways including cutting spark or fuel. The redline is there ...


3

Rev limiter is a bit of a misnomer since maximum engine RPM is a function of airflow. However there are such things as fuel and spark cut off which will disable either injectors or coil packs as a result of going over a predefined RPM (this also happens on deceleration). Doing a little research I found a patent that dates back to 1980 (https://www.google....


2

I would expect a mass market car from the 1990s to have a rev limiter of some sort. But...as other posters have stated a rev limiter won't prevent over revving due to downshifting. Having said that it would require very aggressive downshifts to over rev your engine and it is fairly likely that you are going to damage or at least reduce the life of other ...


2

As stated by Steve, downshifting when the vehicle speed is too high for the gear selected will over-rev any engine. The rev limiter only stops the engine going too fast under its own power. Non-injected engines do sometimes have rev limiters built into the ignition system, you'll have to investigate your own engine specification I think.


2

Based on your description and assuming you have a manual tranmission car, it looks like your clutch is worn out and slipping. Driving like this with an over-revving engine and a slipping clutch will only make things worse and more expensive to fix because other parts will now wear out and fail too. Get your clutch replaced ASAP.


2

I'll admit that I don't have experience with these rev limiters, and I'm drawing conclusions from other experience. That said... On cars with catalytic converters in the exhaust, when the engine detects a misfire, the check engine light flashes rather than just coming on steady to let you know there is an immediate, important issue. The idea is that when ...


2

You are being overly paranoid. While this action isn't good for the engine, it won't harm it. There's a redline for a reason, that being an engine speed you should not exceed. You weren't exceeding this level, so there should be no issue. Engines are designed to take abuse over the long haul. Manufacturers build in a margin of error to help protect the ...


1

Please no; don't do that. Use something like "Shell Rotella" with the proper detergents and let the oil do the work - over a long drive. I'm not sure what oil your owner's manual specifies, but use those oils and drive normally. 3 seconds of revving on a cold start isn't going to "remove" much carbon. You would be much better off with frequent oil ...


1

Every automatic drops in rev´s a little, when in "drive". The torque-converter adds some load to the engine. It should not stall though - if it does, there is either something wrong with your motors idling state or your transmission has a problem which results in an unusually high load. To prevent further damage, make sure to check transmission fluid ...


1

P0726 fault code can be caused by: A failed engine input speed sensor A failed transmission output speed sensor A short or open in the wiring harness to one of the sensors A loose connection to one of the sensors A faulty crankshaft position sensor A faulty shift solenoid Dirty, contaminated or low transmission fluid


1

The limiter does not cause any damage. How you use the limiter, and how often you wind the engine to said limit is a completely different question. As a generality, it is not going to be detrimental for you to set a limit which is relative for your build. Being greedy and setting it too high is asking for trouble, obviously. Cutting Ignition is far ...


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